Wood-preserving solution.



P. HASSELMANN.

WOOD PRESBRVING SOLUTION.

APPLICATION FILED MAY 11, 1909.

97 1 1 94, Patented Sept. 27, 1910.

WITNESSES. lNl/E/VTOR FRITZ HASSfLMA/VA/ 9 7% BY WibP/M Q mm A TTOR/VEVS Es PATENT OFFICE.

FRITZ HASSEL MANN, OF MUNICH, GERMANY.

WOOD-PRESERVING SOLUTION.

Specification of Letters Patent. Patented Sept. 27, 1910.

Application filed May 11, 1909. Serial No. 495,212.

- nate wood, whether fresh or seasoned. The

application of my material to wood to be preserved should preferably be made according to a method which I have invented and which I describe herein.

Impregnating wood with solutions of iron salts and alum 1n the presence of kainite, for the purpose of preserving the same, is well known, having been patented to me in the United States June 6, 1899, and numbered 626,538. Without the kainite such solutions have been found inca able of penetrating the wood to a depth su cient to bring about its artificial petrification and even with the addition of kainite, which -mineral often contains a sulfate of potassium and magnesium as well as a certain percentage of magnesium chlorid, satisfactory results are not to be attained. This failure is chiefly due to the formation of iron-sulfur salts resulting from the dilution of the solution which occurs in boiling processes owing to the condensation of steam; or which takes place in cases where the solution is v'er weak. These iron sulfur salts rot the woo which, therefore, instead of bein preserved, is only destroyed the more quick y. Often free sulfuric acid is formed as well as iron sulfur salts and this acid attacks the wood fibers and the vessel containing the solution so that neutralization by an'addition of suitable reagents becomes necessary.

According to my invention and the method herein set forth the defects j ust-mentioned are avoided and a method and material is provided by means of which wood, whether fresh or well seasoned, is very perfectly preserved. The invention applies pitrtgaularly to resinous woods, as, for examp e, r.

A special advantage of my invention is that it enables the wood to be given a certain degree of hardness without sacrificing anythin with respect to its preservation and wit out afl'ectin its color.

-Referring to the rawings Figure 1 is a front elevation and Fig. 2 a transverse sec tion illustrating an arrangement of apparatus by means of which my invention may be carried out.

The wood a which is to be treated, is arranged in alternate layers in the usual manner upon a truck 5 arranged to run upon suitable rails c laid in a boiler d. This boiler may be heated by a fire maintained in fire box 6. If the wood to be treated is fresh,

'or only partly seasoned, it may be run into the boiler without previous preparation other than taking off the bark; but if the wood is old or has been used for any purose, it is always best to expose fresh suraces by planing or other equivalent method, since in surfaces which have been exposed for any length of time the pores of the wood are apt to be clogged and closed so as to absorb with difliculty, if at all. The solution f with which the boiler is partially filled, and with which the wood is to be impregnated should consist preferably of about l%% 0 iron chlorid (Fe Cl about 2% of ammonium alum, and from 1?,-% to 2% of magnesium chlorid, the solution being thus employed at a concentration of about 5%. A sufficient amount of solution should be used to completely cover the wood and preferably to have a depth over the top of the wood equal to about the diameter of the boiler.

The heating should be regulated so as to raise the solution to a temperature of from 80 to 100 C. At this temperature the albumen contained in the wood will coagulate and the rosin and other sap constituents will be chemically transformed; fungi and other living organisms will of course be absolutely destroyed. The solution which is absorbed tends to preserve and harden the cell walls and cause the cell structure as a whole to become of greater density and closer texture; briefly a species of petrification takes place. The wood so prepared will take a very durable and high polish similar to that given to agate or other hard minerals; this makes wood so treated desirable for furniture and in the arts generally since veneer becomes superfluous. As the solution is absorbed by the wood-in the course of the treatment, its level gradually sinks and provision is therefore made for supplying an additional quantity of solution from time to time to maintain Said level constant. This supply is controlled automatically by means of a float arrangement comprising a float 9 connected through a chain and lever to a valve 72. closing an inlet pipe 21 leadin from a suitable. reservoir (not shown) w ich contains the reserve su ply of solution. As the level sinks, the va ve is opened by the falling float, and remains open until the rise of love resulting from the incoming supply again closes the valve.

In order to secure the best resultsthe solution should be continuously agitated dur-' ing the impre natin rocess so as to keep it homogeneous. If %his is not done the heavier metal salts will deposit more densel at the bottom than at the top and color e fects in particular will be uneven. This agitation is a necessary incident of heatin the boiler by direct firing, as shown in the rawings, since convection currents are of course established which keep the liquid in circulation. In case any mode of heating is used which does not establish convection currents, the system of coiled perforated pipes 7' may be used; into these ipes dry air may be forced and this air, a ter rising through the solution, will leave the boiler through the safety valve h at the to If hot air 1s used the pipes will serve both to heat and to stir the so ution. Or, a fan arrangement 7: giayl be used to agitate the impregnating The wood should be allowed to remain in the solution at the temperature previously mentioned for from two to five hours, the exact time depending upon the quality, dimensions and intended use of the wood which is being treated. At the end of this time the boiler is allowed to cool slowly and during this cooling a further absorption of solution will take place. Proceeding in this way I prevent surface cracks such as might later occur and particularly cracking of the Wood near its surfaces. Cooling having taken place, the wood should be withdrawn from the boiler, drained and then carefully dried, either by stacking it in the open air, or in special'and suitable drying chambers. During this drying o eration a chemical change takes lace an the solution is permanently fixe so that it cannot be washed out even if immersed in salt Water. The color will depend upon the relative proportions of the constituents used to make up the solution. Silver rays, ellows or browns, as also any shades ying etween these colors are readily obtained in this way.

It will, of course, be understood that substances capable of conferring special desired properties upon the Wood may often be added to the solution with desirable results. For example, I may add schoenit for the purpose of keeping out ants, teredos and other insects. This is particularly important when wood is to be used in the tropics. Schoenit is also useful in that it gives increased hardness and impzoved fire-resisting qualities to wood; it can used for this purose in place of ammonium alum, thus prov- 1ng convenient in, places where the latter, for any reason, cannot be obtained. By adding potassium chlorideminent fire proof properties are bestowed upon the wood; potassium chlorid also has an effect upon color tints, especially when used with firs and pines and b its addition causes said tmts to be produce of a dark gray, dark green and other dark shades. The exact tint produced depends upon the characteristics of the wood itself. The same solution may be re eatedly used; any precipitated residue sho d, however, be removed after each treatment before additional or supplemental solution is introduced and after 7 to 10, treatments the entire body of solution. in the boiler should be renewed or purified preferably chemi call 4 The improvements herein set forth are valuable in connection with wood of all kinds, but of special value in connection with wood rich in rosin, as for exam le the fir, pine and similarwoods. I find t at fir particularly, when treated according to my method, acquires in many respects the qualit-ies of oak. This is of manifest commercial importance owing to the much larger supply of fir than oak.

In the specification preceding I have glven certain preferred proportions, which I have found to be the most satisfactory 1n pracfor the solution in carrying out this my but I have also found that these be varied somewhat withtice, mvention proportions ma out losing too argely the valuable proper- I ties desired, and I do not confine myself thereforenecessarily to the exact proportions which have been set forth in the specification as preferable, but claim as my invention:

1. A solution for preservm wood, said solution containing iron chlori ammoniumalum and magnesium chlorid in substantially the proportions specified.

2. A solution for preserving wood, said solution containing approximately 1.5% of iron chlorid, 2% of ammonium alum and from 1.5 to 2% of magnesium chlorid.

3. A solution for preserving wood, sa d solution bein composed of a solutlon m which iron 0 lorid, ammonium alum, and magnesium chlorid have a concentration of approximately 5% to 5.5%.

In testimony whereof I have hereunto set my hand in the presence of two subscrlbmg Witnesses.

, FRITZ HASSELMANN.

Witnesses:

Louis D. MUELLER, MATHILDE K. HELD. 

